PART 1 • LEVEL 03

➗ Operators & Expressions

Learn how Python combines values, performs calculations, compares results and builds logical decisions while following precise precedence rules.

⏱ 80–95 minutes📚 8 concepts💻 5 programs🧠 6-question quiz

Start Lesson ↓Jump to Problems

score_check.pyPython 3

theory = 78
lab = 86
average = (theory + lab) / 2
eligible = average >= 60 and lab >= 70

print(f"Average: {average}")
print(f"Eligible: {eligible}")

OUTPUTAverage: 82.0
Eligible: True

LEARNING OUTCOMES

By the End of This Level

You will be able to construct and evaluate Python expressions accurately.

Use arithmetic and assignment operators correctly.

Predict results using precedence and associativity.

Build comparison and logical expressions.

Recognize membership and identity operations.

BUILD RESULTS

Operators, Operands and Expressions

An operator tells Python which operation to perform. The values used by the operator are operands, and their complete combination is an expression.

In total = price * quantity, price and quantity are operands, * is the operator, and price * quantity is the expression whose result is assigned to total.

Expression

A valid combination of values, variables, operators and function calls that Python evaluates to produce one value.

Arithmetic12 + 8 → 20

Comparison75 >= 40 → True

LogicalTrue and False → False

Membership"Py" in "Python" → True

CALCULATE

Arithmetic Operators

Operator	Meaning	Example	Result
`+`	Addition	`10 + 3`	`13`
`-`	Subtraction	`10 - 3`	`7`
`*`	Multiplication	`10 * 3`	`30`
`/`	True division	`10 / 3`	`3.333...`
`//`	Floor division	`10 // 3`	`3`
`%`	Remainder	`10 % 3`	`1`
`**`	Exponentiation	`10 ** 3`	`1000`

EXAMPLE 1

Split Total Seconds

total_seconds = 3672
hours = total_seconds // 3600
remaining = total_seconds % 3600
minutes = remaining // 60
seconds = remaining % 60

print(hours, minutes, seconds)

OUTPUT

1 1 12

Division detail

/ returns a floating-point result. // returns the mathematical floor, so negative values may move to the next smaller integer: -7 // 2 is -4.

EVALUATION ORDER

Precedence and Associativity

Precedence decides which kind of operator is evaluated first. Associativity decides the direction when operators have the same precedence.

1Parentheses( )

→

2Exponent**

→

3Multiply / Divide* / // %

→

4Add / Subtract+ -

EXAMPLE 2

Trace the Expression

result = 10 + 2 * 3 ** 2
print(result)

grouped = (10 + 2) * 3 ** 2
print(grouped)

OUTPUT

28
108

DEFAULT PRECEDENCE

10 + 2 * 3
# 10 + 6
# 16

Multiplication runs before addition.

EXPLICIT GROUPING

(10 + 2) * 3
# 12 * 3
# 36

Parentheses make the intended order unmistakable.

COMPARE VALUES

Comparison Operators

A comparison expression evaluates to the Boolean value True or False.

Operator	Question	Example	Result
`==`	Are they equal?	`5 == 5`	`True`
`!=`	Are they different?	`5 != 3`	`True`
`>`	Greater than?	`8 > 10`	`False`
`<`	Less than?	`8 < 10`	`True`
`>=`	Greater than or equal?	`40 >= 40`	`True`
`<=`	Less than or equal?	`12 <= 9`	`False`

Do not confuse them

= assigns a value, while == compares two values for equality.

COMBINE CONDITIONS

Logical Operators

🔗

`and`

True only when both operands are true.

🔀

`or`

True when at least one operand is true.

🔄

`not`

Reverses the truth value of its operand.

⚡

Short-circuiting

Python stops as soon as the final logical result is known.

EXAMPLE 3

Training Eligibility

attendance = 82
test_score = 68
fees_due = False

eligible = attendance >= 75 and test_score >= 60
blocked = fees_due or not eligible

print("Eligible:", eligible)
print("Blocked:", blocked)

OUTPUT

Eligible: True
Blocked: False

UPDATE VALUES

Assignment Operators

Augmented assignment performs an operation and stores the result back in the same variable.

Long form	Short form	Meaning
`score = score + 5`	`score += 5`	Add and assign
`stock = stock - 1`	`stock -= 1`	Subtract and assign
`price = price * 2`	`price *= 2`	Multiply and assign
`value = value / 10`	`value /= 10`	Divide and assign
`count = count % 5`	`count %= 5`	Remainder and assign

EXAMPLE 4

Update a Learning Score

score = 50
score += 20
score -= 5
score *= 2

print(score)

OUTPUT

RELATIONSHIPS

Membership and Identity Operators

MEMBERSHIP

`in` and `not in`

Check whether a value occurs inside a sequence or collection.

"Py" in "Python"       # True
"Java" not in "Python" # True

IDENTITY

`is` and `is not`

Check whether two references point to the same object.

result = None
print(result is None)   # True

BEST PRACTICE

Equality vs Identity

Use == for equal values. Use is mainly for singleton objects such as None.

score == 100
result is None

DEBUGGING CORNER

Common Operator Mistakes

Assignment

score = 50

Use ==, not =, when you intend to compare values.

Precedence

total / count + 1

Add parentheses when the required grouping is total / (count + 1).

Logic

age >= 18 or score >= 60

Use and if both requirements must be satisfied.

Evaluate safely:1. Mark operands2. Apply parentheses3. Follow precedence4. Check intermediate types5. Verify the result

QUICK REVISION

📌 Operators & Expressions — Quick Revision

Review the complete Level 3 lesson before attempting the quiz and programming problems.

An expression evaluates to a single value.

/ performs true division; // performs floor division.

% produces a remainder and ** performs exponentiation.

Parentheses provide the clearest control over evaluation order.

Exponentiation is evaluated before multiplication and addition.

Comparisons produce True or False.

and requires both conditions; or requires at least one.

not reverses a truth value.

Augmented assignment updates and stores a value concisely.

Use == for equality and is mainly with None.

KNOWLEDGE CHECK

Level 3 Quick Quiz

Select one answer for every question, then check your score.

6 Questions

1What is the result of 17 // 5? 3.4 3 2 4

2What is 2 + 3 * 4? 20 24 14 11

3Which operator compares two values for equality? == = is in :=

4What is True and not False? False None Error True

5Which statement is equivalent to score = score + 10? score =+ 10 score += 10 score == 10 score ++ 10

6Which is recommended for checking whether result has no value? result == 0 result in None result is None result = None

PRACTICE

🎯 5 Programming Problems — Operators & Expressions

Use the displayed sample inputs. Write expressions carefully, run them, and check the exact expected output before viewing the official program.

📈 Operators Practice Progress

Solved0 / 5

Completed with Solution0

Total Score0 / 500

Completion0%

A problem counts as Solved when its output passes before the official solution is opened.

1. CodeBhavya Book Bill

Read the price and quantity, then display the total bill.

Sample input: 120, 3Expected output: Total = 360

💡 Multiply price by quantity.

Official Python Program

price = int(input())
quantity = int(input())
total = price * quantity
print("Total =", total)

2. Average of Three Marks

Read three marks and display their arithmetic average.

Sample input: 78, 85, 92Expected output: Average = 85

Official Python Program

mark1 = int(input())
mark2 = int(input())
mark3 = int(input())
average = (mark1 + mark2 + mark3) / 3
print("Average =", average)

3. Simple Interest

Read principal, annual rate and time, then calculate simple interest.

Sample input: 10000, 5, 2Expected output: Simple interest = 1000

💡 Use principal * rate * time / 100.

Official Python Program

principal = float(input())
rate = float(input())
time = float(input())
interest = principal * rate * time / 100
print("Simple interest =", interest)

4. Seconds into Time

Convert total seconds into hours, minutes and remaining seconds.

Sample input: 3672Expected output: Three labelled lines: 1, 1, 12

💡 Use // for completed units and % for the remainder.

Official Python Program

total = int(input())
hours = total // 3600
remaining = total % 3600
minutes = remaining // 60
seconds = remaining % 60
print("Hours =", hours)
print("Minutes =", minutes)
print("Seconds =", seconds)

5. Training Eligibility

A student is eligible when age is at least 18 and score is at least 60. Display the Boolean result.

Sample input: 20, 75Expected output: Eligible = True

💡 Join the two comparisons with and.

Official Python Program

age = int(input())
score = int(input())
eligible = age >= 18 and score >= 60
print("Eligible =", eligible)

KEY TAKEAWAY

🎯 Make Every Expression Intentional

1Identify

Know each operand and its data type.

→

2Group

Use parentheses to express the intended order.

→

3Evaluate

Follow precedence one operation at a time.

→

4Verify

Check both the result and its type.

Correct expressions are not guesses. They are small, traceable calculations whose operands, operators and evaluation order are all understood.

INTERACTIVE LEARNING

🎬 Expression Evaluation — Visual Flow

Watch Python reduce 10 + 2 * 3 ** 2 one precedence level at a time.

PROGRAM TRACING

🔎 Program Tracing — Operator Results

Trace arithmetic, remainder and comparison results as variables and output change.

INTERVIEW PREPARATION

🎤 Operators & Expressions — Interview Questions

Answer aloud before opening each explanation.

What is the difference between / and //?

/ performs true division and returns a floating-point result. // performs floor division and returns the floor of the quotient.

What is operator precedence?

What is associativity?

How do and and or differ?

and requires both conditions to be truthy. or requires at least one condition to be truthy.

What is short-circuit evaluation?

Python stops evaluating a logical expression when the remaining operands cannot change its result—for example, after a false operand in an and expression.

When should is be used instead of ==?

Use == to compare values. Use is to compare object identity, most commonly when checking a singleton such as None.

EXTRA TIPS

💡 Operators & Expressions — Extra Tips

01
Use parentheses when they make the intended formula easier to read, even if precedence already gives the same result.
02
Trace one intermediate value at a time when an expression produces an unexpected answer.
03
Remember that / returns a float even when the division is exact.
04
Use // and % together when splitting a total into units and remainders.
05
Write complete comparisons on both sides of logical operators.
06
Prefer clear Boolean variable names such as is_eligible or has_access.

EXTRA PRACTICE

✍️ Operators & Expressions — Extra Practice Questions

Predict 5 + 2 * 3 ** 2 without running it, then verify your trace.
Read two numbers and display all seven arithmetic-operation results.
Read a three-digit number and display the sum of its digits using // and %.
Convert a total number of minutes into hours and remaining minutes.
Write an expression that checks whether a number lies from 10 through 50, inclusive.
Show how parentheses change the result of 20 - 6 / 2 + 3.
Use augmented assignment to apply a bonus, penalty and multiplier to a score.
Check whether the text "Python" contains "tho".
Build a Boolean expression for age at least 18, attendance at least 75 and no pending fee.
Explain why 2 ** 3 ** 2 is different from (2 ** 3) ** 2.

LEVEL 3 CHECKPOINT

Operators & Expressions Complete

When you can predict precedence, choose suitable operators and solve all five programs without help, mark this level complete and continue.

Continue to Level 4 →

➗ Operators & Expressions

By the End of This Level

Operators, Operands and Expressions

Arithmetic Operators

Split Total Seconds

Precedence and Associativity

Trace the Expression

Comparison Operators

Logical Operators

and

or

not

Short-circuiting

Training Eligibility

Assignment Operators

Update a Learning Score

Membership and Identity Operators

in and not in

is and is not

Equality vs Identity

Common Operator Mistakes

📌 Operators & Expressions — Quick Revision

Level 3 Quick Quiz

🎯 5 Programming Problems — Operators & Expressions

Python Code Editor

Program Output

Test Case

Python Code Editor

Program Output

Test Case

Python Code Editor

Program Output

Test Case

Python Code Editor

Program Output

Test Case

Python Code Editor

Program Output

Test Case

🎯 Make Every Expression Intentional

🎬 Expression Evaluation — Visual Flow

🧮 How Python Evaluates an Expression

1. Read the Complete Expression

🔎 Program Tracing — Operator Results

🎤 Operators & Expressions — Interview Questions

💡 Operators & Expressions — Extra Tips

✍️ Operators & Expressions — Extra Practice Questions

Operators & Expressions Complete

`and`

`or`

`not`

`in` and `not in`

`is` and `is not`